With the development of the electronic equipment, a semiconductor integrated circuit employed in a CPU of a computer and a digital television has been improved in terms of its processing speed. Particularly, an image processing LSI is developing in terms of an increasing processing speed, and also a further integration is advanced. There is also a demand for a down-sizing and an increase in the number of I/O terminals.
Under such a current situation that the down-sizing and the increase in the number of I/O terminals is coincidentally developing, the down-sizing of terminal pitches and/or narrower pitching of the terminals is further developing, which causes a difficulty in a mounting of a semiconductor integrated circuit (i.e., LSI) on a packaged circuit board.
As a packaged circuit board of the LSI, a build-up wiring board is generally used wherein a plurality of build-up layers are laminated, each build-up layer comprising an interlayer insulator, a via hole, and a copper foil wiring layer on both sides of a core substrate having a high elastic modulus (for example, Patent Document 1 discloses that the core material of the build-up substrate has 100 times as high elastic modulus as that of the build-up layer thereof).
Particularly as for the latest CPU, miniaturization thereof is developing to the extent of 22 nm, and the increase in the number of I/O terminals and the scaling up of circuits are also remarkably developing. For a server use, the semiconductor integrated circuit chip is rather becoming larger. In the course of more use of large-sized chips, such a problem may arise that a solder connection can come off the substrate due to a substrate warpage occurred during a manufacturing process thereof, or due to a substrate warpage attributed to a thermal history upon a LIS chip mounting process even in a case where the normal build-up substrate is used.
On the other hand, a ceramic substrate with an excellent thermal conductivity may be used as a circuit board for LSI chip mounting. The ceramic substrate is excellent in terms of a heat resistance and a moisture resistance. The ceramic substrate also has a small thermal expansion coefficient and a less warpage characteristic. Thus, the ceramic substrate is suitable for a metal connection such as soldering. However, it is hard for the ceramic substrate to be sintered in a case where it has a large size. Further, a cracking tends to occur in the ceramic substrate, and thus the ceramic substrate is not suitable for a thinning of the substrate (see Patent Document 2).
The warpage and cracking of the substrate tend to more frequently occur when the size of the ceramic substrate becomes larger. In this point of view, the current ceramic substrate is provided in a size of about 100 mm square. Even if a large ceramic substrate is provided by a sintering process, such large ceramic substrate tends to be cracked with ease, and thereby a handling thereof becomes very difficult. Therefore, a hard substrate has to be realized only with a larger thickness thereof.
Recently, there has been proposed a composite substrate with its core substrate built up, in which a ceramic substrate is disposed in an opening of a core portion (core) of a build-up substrate, and also a resin material is provided on both sides thereof. For example, Patent Document 3 discloses that a ceramic portion is disposed in a region provided in a core substrate of a polymer material. In this prior art of Patent Document 3, a ceramic plate having a small thermal expansion coefficient is disposed in the opening of the core substrate to relax a difference in thermal expansion between a semiconductor and the polymer material, and thereby a disconnection therebetween is avoided.    PATENT DOCUMENT 1: JP 2002-319764    PATENT DOCUMENT 2: WO 2009/087845    PATENT DOCUMENT 3: JP 2005-039217
In a case where a large-sized semiconductor bare chip is mounted on a build-up substrate, it is very hard to avoid an influence of the warpage generated at a point in process time before and after the mounting of the semiconductor bare chip on the substrate. In this case, the ceramic substrate having a high elastic modulus is effectively used to avoid the above influence. The ceramic substrate with its high elastic modulus is desirable for a manufacturing of the build-up substrate. However, there is a difference in size between the ceramic substrate and the build-up substrate. For example, the ceramic substrate has a size of about 100 mm×about 100 mm, whereas a printed circuit board, which is a typical build-up substrate, has a size of about 340 mm×about 510 mm. Such size difference has a negative influence on the manufacture of the build-up substrate. Specifically, the manufacturing of the build-up substrate is substantially affected by the size of the ceramic substrate, which is not sufficient in terms of productivity. Particularly, since the ceramic substrate has a “small size” of about 100 mm square, the build-up substrate using such ceramic substrate should be manufactured based on such a small size unit, which inhibits a high productivity of the build-up substrate.
In this point, although an attempt can be made to increase the size of the ceramic substrate, a mere increase of the size of the ceramic substrate may induce a cracking or breaking of the substrate as mentioned above. The avoidance of the cracking or breaking may cause a difficulty in conveyance of the substrate during the production process of the substrate, or may require too large thickness of the substrate. A setter plate for a sintering process to be used in the manufacture of a large-sized ceramic substrate is usually difficult to be produced. Even if such setter plate is produced, it will become very expensive, or a high degree of its accuracy will be required in terms of smoothness since the setter plate can directly have a negative influence on the warpage of the ceramic substrate.
Meanwhile, another attempt can be made to employ the above-mentioned “composite substrate with its core substrate built up, in which the ceramic substrate is disposed in the opening of the core substrate of the build-up substrate, and also the resin material is provided on both sides of the core substrate”. However, it is difficult to accurately dispose the ceramic substrate in the opening of the core, and also it is very difficult to perform an alignment of the build-up. This results in a low productivity.